There was no "factory installed radio / antenna", but there is a radio and antenna listed in the Pantera parts book. D16Y 18805-A is a radio, speakers, and antenna kit for the Pantera. It used a vertical dial Bendix radio. I've only seen a few of these, I have the radio, but not the speakers or antenna. D16Y 18813-A is listed as an antenna, but I don't know what it looks like. The Bendix radio has an extra lead to operate a power antenna, but I don't know if either of those part numbers included a power antenna. The D16Y 18813-A says "manual", so I'm guessing that's a telescoping type antenna.
Here's a picture of the Bendix radio.
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